Briquetting apparatus

ABSTRACT

Material to be briquetted is first fed through precompacting rolls to form a precompacted strip of material guided by a pair of endless belts to the nip of briquetting rolls mating to form a line of briquetting pockets. Resulting briquettes have uniform density regardless of the pocket in which they were formed.

United States Patent [191 I Holowaty Feb. 12, 1974 BRIQUETTING APPARATUS [75] Inventor: Michael O. Holowaty, Crown Point,

Ind.

[73] Assignee: Inland Steel Company, Chicago, Ill.

[22] Filed: Mar. 27, 1972 [21] Appl. No.: 238,380

[52] [1.5. CI. 44/13, 44/11 [51] Int. Cl B30b 11/00, C101 5/22 [58] Field of Search 44/2, ll-l3;

75/44 R; IOO/DIG. 6, 176

[56] References Cited UNITED STATES PATENTS 12/1972 Stanton 44/12 Mautsch 75/44 R Komarek 44/13 X Primary ExaminerC. F. Dees Attorney, Agent. or FirmMerriam. Marshall, Shapiro & Klose [57] ABSTRACT Material to be briquetted is first fed through precompacting rolls to form a precompacted strip of material guided by a pair of endless belts to the nip of briquetting rolls mating to form a line of briquetting pockets Resulting briquettes have uniform density regardless of the pocket in which they were formed.

17 Claims, 6 Drawing Figures PATENTH] FEB I 21974 BRIQUETTING APPARATUS BACKGROUND OF THE INVENTION The present invention relates generally to apparatus for forming briquettes, e.g., briquettes of coking material, and more particularly to an apparatus for forming briquettes having a uniform density from briquette to briquette.

Conventional briquetting apparatus generally comprises a pair of counter-rotating briquetting rolls each containing a series of recesses or indentations which mate with corresponding recesses on the other counterrotating roll to define, at the nip of the two rolls, a line of pockets extending across the width of the rolls for forming, into briquettes, material fed into the nip of the briquetting rolls.

The material to be briquetted is generally pasty and is fed to the briquetting rolls typically from a hopper containing a screw feed or auger which forces the material out of an opening at the bottom of the hopper and directs it toward thev nip of the briquetting rolls. The feed from the hopper or other feeding device is generally in the shape of a descending column of material having a round or eliptical horizontal cross-section overlying only those pockets in the middle of a line of pockets.

I a second in which a given line of pockets is positioned to be filled with feed material. In this short period of time, the descending column of feed material must be evenly distributed, not only along the entire line of pockets, but also across the varying transverse dimension of each pocket. With a descending column of feed material having a circular or eliptical cross-section, and positioned relative to the line of pockets as described above, uniform distribution of the feed material from pocket to pocket in a line of pockets, and across a given pocket, is extremely difficult, if not impossible, even with forced screw feeding of the material undergoing briquetting. The pockets in the middle of the line will be overfed, and the pockets at the ends of the line will be underfed. The result is briquettes which vary in density, depending upon the pocket in which formed.

SUMMARY OF THE INVENTION A briquetting apparatus in accordance with the present invention comprises a pair of precompacting rolls located along the path of the descending column of material, between the feed hopper and the briquetting rolls. The precompacting rolls form the column of material into an at least partially compacted strip having sity, regardless of the pocket, along the line of pockets, in which they were formed.

Located between the precompacting rolls and the briquetting rolls are guide means in the form of a pair of endless belts each located on one side of the precompacted strip and in contact therewith, for preventing the precompacted strip of material from folding on itself as it moves between the precompacting rolls and the briquetting rolls.

The speed of rotation of the two pairs of rolls and the speed of the pair of belts are all controlled relative to each other so that a point on either of the two belts or on any of the rolls in the two pairs of rolls all move at the same speed. This prevents the precompacted strip of material from tearing or backing up as it moves be tween the two pairs of rolls.

Other features and advantages are inherent in the structure claimed and disclosed or will become apparent to those skilled in the art from the following detailed description in conjunction with the accompanying diagrammatic drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a briquetting apparatus constructed in accordance with an embodiment of the present invention;

FIG. 2 is a fragmentary view illustrating an embodiment of precompacting rolls in accordance with the present invention;

FIG. 3 is a fragmentary view illustrating one embodiment of briquetting rolls;

FIG. 4 is a fragmentary view of another embodiment of briquetting roll;

FIG. 5 is a horizontal sectional view illustrating an embodiment of guide belts in accordance with the pres ent invention; and

FIG. 6 is a fragmentary view showing a briquetting pocket.

DETAILED DESCRIPTION INCLUDING PREFERRED EMBODIMENTS Referring initially to FIG. 1, dry material 10 and binder 12 are fed into a blender-homogenizer 13 for thorough mixing. If desired, additional dry material II may be fed into the blender-homogenizer for mixing with dry material 10 and binder 12. The resulting mixed material is introduced into a hopper 14 from which the material is force fed by a feeding screw or auger 15 toward the nip of a pair of counter-rotating briquetting rolls 23, 24 having recesses 29 (FIG. 3) which mate the nip of the rolls to define a line of pockets 30.

The material leaves the bottom of hopper 14 as a descending column 16 having a horizontal cross-section typically in the shape of a circle or elipse. Referring to FIG. 3, the cross-sectional dimensions of column 16 are less than the width of the briquetting rolls and greater than the transverse dimension of a pocket 30.

A pair of precompacting rolls 17-18 are located along the path of the descending material, between feed hopper l4 and briquetting rolls 23, 24. The space between the precompacting rolls l7, 18 is less than the corresponding cross-sectional dimension of column 16; and rolls 17, 18 form the material into an at least partially compacted strip 19. Strip 19 has a width no greater than and preferably the same as the width of the briquetting rolls 23, 24 (i.e., the dimension of a line of pockets 30) and a thickness at least percent thicker than the largest transverse dimension 31 of a pocket 30 (FIG. 6).

Located between precompacting rolls 17, 18 and briquetting rolls 23, 24 are guide means in the form'of a pair of moving endless belts 21, 22. Each belt 21, 22 is located on a respective opposite side of strip 19 and is in contact therewith. Belts 21, 22 prevent the strip of material from folding on itself as it moves between the precompacting rolls and the briquetting rolls; and the belts guide strip 19 toward the nip of the briquetting rolls 23, 24, where the strip is evenly distributed along the line of pockets 30. The resulting briquettes 25 have uniform density. no matter in which pocket, along the line of pockets 30, a briquette is formed.

Typical examples of dry. starting materials 10, 11 include partially or totally devolatilized bituminous coal particles typically having a diameter of less than A; inch. The percent of volatiles in bituminous coal is in the range -40 percent. The coal may be good coking coal or non-coking coal.

Typical binders 12, for use with dry materials of the type described in the preceding paragraph, include coal tar, tar pitch, petroleum asphalt, sugar molasses, and the like. The 'drystarting materials account for about 80-90 wt. percent of the material fed into blenderhomogenizer 13, and the binder constitutes the rest.

Another example of dry starting material is lime fines. Typical binders for use with lime fines are tallow, asphalt or residual oil.

Apparatus in accordance with the present invention can be used with any briquettable material, so long as the material, if dry, has been preplasticized in a blender-homogenizer 13 with a binder.

Some materials, such as fly ash, bone ash, clay or surgar, do not require a binder. Even when dry they have a natural tendency to bind into a briquette. In such a case, the blender-homogenizer would be unnecessary.

Blender-homogenizer 13 is of conventional construction. Examples thereof include a conventional pug mill or conventional muller.

Hopper 14 and force feeding screw or auger 15 are of conventional construction heretofore utilized for the feeding of material to be briquetted.

When dry feed materials, not requiring a binder are used, feeding screw 15 is not required, the latter being utilized only with pasty material which doesnt flow readily.

Precompacting rolls 17, 18 may have a smooth circumference, or may be provided with grooves or serrations 27 (FIG. 2) extending side-by-side around the circumference of the rolls. When the precompacting rolls have a smooth circumference, the precompacted strip 19 has a rectangular horizontal cross-section (not shown). When the precompacting rolls have serrations 27, the precompacted strip 19 has a horizontal crosssection as shown in FIG. 5.

Similarly, guide belts 21, 22 may have smooth surfaces for contacting strip 19, when the latter has a rectangular cross-section; but, when precompacted strip 19 has a cross-section such as that shown in FIG. 5, then guide belts 21, 22 are provided with grooves or serrations 28, as shown in FIG. 5.

Precompacting rolls 17, 18 are spaced apart with a sufficient gap therebetween so that they form a strip 19 having a thickness at least 10 percent greater than the largest transverse dimension 31 (FIG. 6) of any pocket 30 in the line of pockets at the nip of the briquetting rolls 23, 24.

When strip 19 has the cross-section illustrated in FIG. 5, the shape of the strip corresponds substantially to the shape of the line of pockets 30 at the nip of the briquetting rolls, except that the transverse dimension, along any part of the strip, is at least 10 percent greater than the transverse dimension of the corresponding pocket part on the line of pockets 30.

Strip 19 is provided with a transverse dimension or thickness at least 10 percent greater than the corresponding transverse dimension of the pockets on the briquetting rolls to assure that the briquettes are not only shaped but also undergo additional compaction at the briquetting rolls. Additional compaction is necessary to hold the briquettes together.

In a preferable embodiment, guide belts 21, 22 converge toward each other from the precompacting rolls toward the briquetting rolls, to impart further compaction to strip 19, preferably about a 5 percent compaction.

Guide belts 21, 22 preferably should extend upwardly as closely as possible to the nip between precompacting rolls 17, 18 and downwardly as closely as possible to the nip between briquetting rolls 23, 24, to maximize the function of guide belts 21, 22 in preventing strip 19 from folding on itself as it descends from precompacting rolls l7, 18 to briquetting rolls 23, 24.

Guide belts 21, 22 may also be utilized to apply, to opposite surfaces of strip 19, a substance for facilitating separation of the strip from the belts, as the strip leaves the belts, and for facilitating separation of the material from the briquetting rolls after the material has been compacted into briquettes. A typical separationfacilitating substance is oil. The oil may be sprayed on belts 21, 22 by sprayers 33.

FIG. 3 shows briquetting rolls 23, 24 having essentially square recesses 29 while FIG. 4 shows briquetting rolls 123, 124 having essentially rectangular recesses 129.

Briquetting rolls 23, 24 typically have a diameter in the range 20-30 inches and have anywhere from I to 10 pockets 30 at the nip of the rolls, along the width thereof. The width of a roll is its dimension between ends 35 and 36 (FIG. 3). Each pocket may be from inch to 3 inches wide, for example. (The width of a pocket is the dimension along the width of the briquetting roll). The briquetting rolls typically rotate at a speed in the range 5-50 r.p.m. (20-30 r.p.m. preferably).

The precompacting rolls generally have a diameter in the range 36-60 inches, with a width the same as the width of the briquetting rolls with which they cooperate. A given pair of precompacting rolls have larger diameters than the briquetting rolls with which they cooperate.

Referring to the last two paragraphs, the ratio of the diameter of the precompacting rolls (diameter: 36-60 inches) to the diameter of the briquetting rolls (diameter: 20-30 inches) is (3.6-6/2-3).

The precompacting rolls generally rotate at a speed of about 2-25 rpm. The speed of the precompacting rolls is coordinated with the speed of the briquetting rolls so that the speed of a point on the circumference of a precompacting roll is equal to the speed of a point on the circumference of a briquetting roll.

Similarly, the speed of guide belts 21, 22 is controlled so that a point on either belt 21, 22 moves at the same speed as a point on any of the rolls 17, 18 or 23, 24. If the guide belts move too fast, the strip of precompacted compacted material 19 will be torn; and if the guide belts move too slowly, the strip of material will back up on itself.

To produce a strip of precompacted material 19 of the desired thickness and width, for uniform distribution across the nip of the briquetting rolls, the precompacting rolls l7, 18 should turn, desirably, as slowly as possible consistent with keeping up with the briquetting rolls 23, 24; and, accordingly, the precompacting rolls should have a diameter as large as possible.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom as modifications will be obvious to those skilled in the art.

Whatis claimed is:

1. A briquetting apparatus comprising:

a pair of briquetting rolls including means for forming briquettes:

feed means for directing material to be briquetted toward the nip of said briquetting rolls in a descending column of material having a horizontal cross-section unevenly distributed across the width of said briquetting rolls;

said briquetting rolls defining'a plurality of pockets extending in a line along the nip of said rolls transverse to the direction of descent of said column of material;

said line of pockets having a linear dimension substantially greater than the dimension of said column of material in the same direction;

each pocket in said line of pockets having a varying dimension in a direction transverse to said linear dimension, said varying dimension being substantially less than the dimension of said column in the same direction;

and a pair of precompacting rolls located along the path of said material, between said feed means and said briquetting rolls;

said precompacting rolls comprising means for forming said column of material into an at least partially compacted strip having a cross-section which is evenly distributed along said line of pockets and a strip dimension in the direction of said line of pockets substantially coextensive with the linear dimension of said line of pockets.

2. A briquetting apparatus as recited in claim 1 and comprising:

guide means, located between said precompacting rolls and said briquetting rolls, for preventing said strip' of material from folding on itself as it moves between the precompacting rolls and the briquetting rolls.

3. A briquetting apparatus as recited in claim 2 wherein said guide means comprises:

a pair of moving, endless belt means, with one belt means on each side of said strip and in contact therewith.

4. A briquetting apparatus as recited in claim 3 wherein:

said pair of belt means converge toward each other from said precompacting rolls toward said briquetting rolls to impart an additional compaction to said strip. 5. A briquetting apparatus as recited in claim 3 and comprising: 5 means for rotating said briquetting rolls at a predetermined speed; means for rotating said precompacting rolls so that a point on the circumference of a precompacting roll moves at the same speed as a point on the cirfum-' ference of a briquetting roll; and means for moving each of said belt means so that a point on a belt means moves at the same speed as said point on said precompacting roll. 6. A briquetting apparatus as recited in claim 3 and comprising:

means for controlling the speed of said belt means, relative to the speed of rotation of both of said pairs of rolls, to prevent said strip of material from tearing or backing up as it moves between the two pairs of rolls. 7. A briquetting apparatus as recited in claim 3 wherein:

said precompacting rolls comprise means for preforming said strip of material to provide a horizontal cross-section on said strip corresponding substantially to the shape of said line of pockets; and said belt means comprises means on each belt cooperating to define a space therebetween having a shape, in horizontal cross-section, corresponding to the horizontal cross-section of said strip provided by said precompacting rolls. 8. A briquetting apparatus as recited in claim 7 wherein:

said briquetting rolls include means for imparting additional compaction to said material from said strip.

9. A briquetting apparatus as recited in claim 3 and comprising:

means for applying to opposite surfaces of said strip of material, at said belt means, a substance for facilitating separation of said strip from said belt means, as the strip leaves the belt means, and for facilitating separation of said material from said briquetting rolls after the material has been compacted into briquettes. 10. A briquetting apparatus as recited in claim 1 wherein:

said briquetting rolls include means for imparting additional compaction to said material from said strip. 11. A briquetting apparatus as recited in claim 10 wherein:

said precompacting rolls comprise means for providing said strip of material with a thickness at least 10 percent wider than the largest transverse dimension of any pocket in said line of pockets. 12. A briquetting apparatus as recited in claim 10 wherein:

said precompacting rolls comprise means for preforming said strip of material to provide a horizontal cross-section on said strip corresponding substantially to the shape of said line of pockets. 13. A briquetting apparatus as recited in claim 12 wherein:

said precompacting rolls comprise means for providing said strip of material with a thickness, along any part thereof, at least 10 percent wider than the transverse dimension of a corresponding pocket part on said line of pockets. 14. A briquetting apparatus as recited in claim 1 and comprising:

means for rotating said briquetting rolls at a predetermined speed; and means for rotating said precompacting rolls so that a point on the circumference of a precompacting roll moves at the same speed as a point on the circumference of a briquetting roll. 15. A briquetting apparatus as recited in claim 1 wherein:

said precompacting rolls have a diameter substantially larger than the diameter of said briquetting rolls and a width no greater than the width of the circumference of a briquetting roll. 

2. A briquetting apparatus as recited in claim 1 and comprising: guide means, located between said precompacting rolls and said briquetting rolls, for preventing said strip of material from folding on itself as it moves between the precompacting rolls and the briquetting rolls.
 3. A briquetting apparatus as recited in claim 2 wherein said guide means comprises: a pair of moving, endless belt means, with one belt means on each side of said strip and in contact therewith.
 4. A briquetting apparatus as recited in claim 3 wherein: said pair of belt means converge toward each other from said precompacting rolls toward said briquetting rolls to impart an additional compaction to said strip.
 5. A briquetting apparatus as recited in claim 3 and comprising: means for rotating said briquetting rolls at a predetermined speed; means for rotating said precompacting rolls so that a point on the circumference of a precompacting roll moves at the same speed as a point on the cirfumference of a briquetting roll; and means for moving each of said belt means so that a point on a belt means moves at the same speed as said point on said precompacting roll.
 6. A briquetting apparatus as recited in claim 3 and comprising: means for controlling the speed of said belt means, relative to the speed of rotation of both of said pairs of rolls, to prevent said strip of material from tearing or backing up as it moves between the two pairs of rolls.
 7. A briquetting apparatus as recited in claim 3 wherein: said precompacting rolls comprise means for preforming said strip of material to provide a horizontal cross-section on said strip corresponding substantially to the shape of said line of pockets; and said belt means comprises means on each belt cooperating to define a space therebetween having a shape, in horizontal cross-section, corresponding to the horizontal cross-section of said strip provided by said precompacting rolls.
 8. A briquetting apparatus as recited in claim 7 wherein: said briquetting rolls include means for imparting additional compaction to said material from said strip.
 9. A briquetting apparatus as recited in claim 3 and comprising: means for applying to opposite surfaces of said strip of material, at said belt means, a substance for facilitating separation of said strip from said belt means, as the strip leaves the belt means, and for facilitating separation of said material from said briquetting rolls after the material has been compacted into briquettes.
 10. A briquetting apparatus as recited in claim 1 wherein: said briquetting rolls include means for imparting additional compaction to said material from said strip.
 11. A briquetting apparatus as recited in claim 10 wherein: said precompacting rolls comprise means for providing said strip of material with a thickness at least 10 percent wider than the largest transverse dimension of any pocket in said line of pockets.
 12. A briquetting apparatus as recited in claim 10 wherein: said precompacting rolls comprise means for preforming said strip of material to provide a horizontal cross-section on said strip corresponding substantially to the shape of said line of pockets.
 13. A briquetting apparatus as recited in claim 12 wherein: said precompacting rolls comprise means for providing said strip of material with a thickness, along any part thereof, at least 10 percent wider than the transverse dimension of a corresponding pocket part on said line of pockets.
 14. A briquetting apparatus as recited in claim 1 and comprising: means for rotating said briquetting rolls at a predetermined speed; and meAns for rotating said precompacting rolls so that a point on the circumference of a precompacting roll moves at the same speed as a point on the circumference of a briquetting roll.
 15. A briquetting apparatus as recited in claim 1 wherein: said precompacting rolls have a diameter substantially larger than the diameter of said briquetting rolls and a width no greater than the width of the briquetting rolls.
 16. A briquetting apparatus as recited in claim 15 wherein: The ratio of diameters of said precompacting rolls to said briquetting rolls is (3.6-6)/(2-3).
 17. A briquetting apparatus as recited in claim 15 and comprising: means for rotating said briquetting rolls at a predetermined speed; and means for rotating said precompacting rolls so that a point on the circumference of a precompacting roll moves at the same speed as a point on the circumference of a briquetting roll. 